/*-------------------------------------------------------------------------
 *
 * win32env.c
 *      putenv() and unsetenv() for win32, which update both process environment
 *      and caches in (potentially multiple) C run-time library (CRT) versions.
 *
 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *      src/port/win32env.c
 *
 *-------------------------------------------------------------------------
 */

#include "c.h"

int
pgwin32_putenv(const char *envval)
{// #lizard forgives
    char       *envcpy;
    char       *cp;
    typedef int (_cdecl * PUTENVPROC) (const char *);
    static const char *const modulenames[] = {
        "msvcrt",                /* Visual Studio 6.0 / MinGW */
        "msvcrtd",
        "msvcr70",                /* Visual Studio 2002 */
        "msvcr70d",
        "msvcr71",                /* Visual Studio 2003 */
        "msvcr71d",
        "msvcr80",                /* Visual Studio 2005 */
        "msvcr80d",
        "msvcr90",                /* Visual Studio 2008 */
        "msvcr90d",
        "msvcr100",                /* Visual Studio 2010 */
        "msvcr100d",
        "msvcr110",                /* Visual Studio 2012 */
        "msvcr110d",
        "msvcr120",                /* Visual Studio 2013 */
        "msvcr120d",
        "ucrtbase",                /* Visual Studio 2015 and later */
        "ucrtbased",
        NULL
    };
    int            i;

    /*
     * Update process environment, making this change visible to child
     * processes and to CRTs initializing in the future.  Do this before the
     * _putenv() loop, for the benefit of any CRT that initializes during this
     * pgwin32_putenv() execution, after the loop checks that CRT.
     *
     * Need a copy of the string so we can modify it.
     */
    envcpy = strdup(envval);
    if (!envcpy)
        return -1;
    cp = strchr(envcpy, '=');
    if (cp == NULL)
    {
        free(envcpy);
        return -1;
    }
    *cp = '\0';
    cp++;
    if (strlen(cp))
    {
        /*
         * Only call SetEnvironmentVariable() when we are adding a variable,
         * not when removing it. Calling it on both crashes on at least
         * certain versions of MinGW.
         */
        if (!SetEnvironmentVariable(envcpy, cp))
        {
            free(envcpy);
            return -1;
        }
    }
    free(envcpy);

    /*
     * Each CRT has its own _putenv() symbol and copy of the environment.
     * Update the environment in each CRT module currently loaded, so every
     * third-party library sees this change regardless of the CRT it links
     * against.  Addresses within these modules may become invalid the moment
     * we call FreeLibrary(), so don't cache them.
     */
    for (i = 0; modulenames[i]; i++)
    {
        HMODULE        hmodule = NULL;
        BOOL        res = GetModuleHandleEx(0, modulenames[i], &hmodule);

        if (res != 0 && hmodule != NULL)
        {
            PUTENVPROC    putenvFunc;

            putenvFunc = (PUTENVPROC) GetProcAddress(hmodule, "_putenv");
            if (putenvFunc)
                putenvFunc(envval);
            FreeLibrary(hmodule);
        }
    }

    /*
     * Finally, update our "own" cache.  This is redundant with the loop
     * above, except when PostgreSQL itself links to a CRT not listed above.
     * Ideally, the loop does visit all possible CRTs, making this redundant.
     */
    return _putenv(envval);
}

void
pgwin32_unsetenv(const char *name)
{
    char       *envbuf;

    envbuf = (char *) malloc(strlen(name) + 2);
    if (!envbuf)
        return;

    sprintf(envbuf, "%s=", name);
    pgwin32_putenv(envbuf);
    free(envbuf);
}
